Such a rotor of a wind power plant is known from DE 10 2006 002 708 B4. The rotor blade is hollow and the reflection means are arranged at the outer wall or at the middle web of the rotor blade. A transmitting unit and a receiving unit are arranged in the rotor hub flush with the cavity and accommodated in a common housing. The fastening of this housing in the rotor hub is not shown.
To measure the rotor deflection, exact alignment is necessary between the transmitter/receiver and the reflector. When mounting the transmitter and receiver in the rotor, this means mounting surfaces machined with very high precision in the rotor. It is desirable that the useful measuring range of the receiver corresponds to the deflection range of the associated rotor blade. This would mean very high requirements in terms of tolerance during the manufacture of the hub, the rotor blade and the connection between hub and rotor blade and for the fastening of the housing of the measuring means.